In order to cope with challenges caused by continuous scaling down of semiconductor devices, such as short channel effects etc., a variety of high-performance devices have been proposed, e.g., SOI devices, FinFETs, and the like.
The SOI devices can suppress the short channel effects due to BOX (Buried Oxide) therein. Further, FD (Fully Depleted) SOI devices can be achieved by the ET-SOI (Extremely Thin-Semiconductor on Insulator) technology. However, SOI including ET-SOI is more expensive and has limited performances.
The FinFET is a three-dimensional device, comprising a fin formed vertically on a substrate, with a channel defined in the fin. The fin may have its height raised without increasing its footprint, resulting in increased current drive capability per unit footprint. However, fins generally have substantially uniform heights across a wafer, and are difficult to be adjusted separately. Thus, it is difficult to separately adjust the drive capability of individual devices in an integrated circuit formed on the wafer.